Method and a device for removing water from the surface of a roller jacket

ABSTRACT

The present invention relates to a method for removing water from a movable roll jacket surface in a wet section of a paper-making machine, which roll jacket surface preferably belongs to a flexible roll jacket in a shoe press, said method comprising the following steps: arranging a spray device next to the roll jacket surface, making available a collecting device which is provided with an opening and collects liquid, moving said roll jacket surface past said spray device, applying a medium onto said roll jacket surface with the aid of said spray device, and collecting liquid in said liquid-collecting device. The invention is characterized in that said medium is sprayed with high kinetic energy onto said roll jacket surface to follow a fluid stream rebounding from the roll jacket surface, so that the liquid is conveyed to said liquid-collecting device.

This application claims the benefit of Provisional application Ser. No.60/273,367, filed Nov. 5, 2001.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for removing water from amovable roll jacket surface in a wet section of a paper-making machine,which roll jacket surface preferably belongs to a flexible roll jacketin a shoe press, said method comprising the following steps:

-   -   arranging a spray device next to the roll jacket surface,    -   setting up a collecting device which is provided with an opening        and collects liquid,    -   moving said roll jacket surface past said spray device,    -   applying a medium onto said roll jacket surface with the aid of        said spray device, and    -   collecting liquid in said liquid-collecting device or        liquid-receiving device.

2. Description of Related Art

In a wet section of a paper-making machine, large quantities of waterhave to be removed from the fiber web. This is done with, inter alia,the aid of pairs of rolls which form a nip for pressing/sucking waterout of the fiber web. A certain amount of water remains behind on theroll jacket surface after the nip. In many situations it is desirable toremove at least the majority of the remaining water before that part ofthe roll jacket surface passes through the nip again.

It is already known, for example from U.S. Pat. Nos. 4,852,209 and5,810,974, to set up spray devices which can clean (and/or cool) a rolljacket surface. However, this known technique does not deal with theproblem of how to remove water from the roll jacket surface.

A press device in a wet section is already known from EP 771,903, wherethe roll jacket surface of one of the roll pairs is sprayed with water,after which a special scraping device (called a doctor blade) removeswater from the roll jacket surface. DE 19860735 shows that it is alsoalready known to arrange a scraping device/doctor blade solely for thepurpose of removing water, i.e. without first spraying the roll jacketsurface. Similar cleaning and dewatering devices are also already knownfrom U.S. Pat. No. 5,520,782, DE 19841637, DE 19860735 and DE 19810800.

However, it is not always desirable to use a scraping member which is indirect contact with the roll jacket surface. In the case of a shoe pressroll, where a flexible roll jacket is used, it may be particularlyundesirable because the flexible roll jacket is often relativelysensitive and expensive.

There is a risk that such a scraping member may destroy the flexibleroll jacket or at least accelerate its wear, in the same way that it canalso cause damage on another type of roll surface.

A further disadvantage of known dewatering devices according to theabove is that they have a very limited effect if the roll jacket surfacefrom which water is to be removed is patterned, i.e. provided withgrooves, for example of the type described in U.S. Pat. No. 4,559,258.

BRIEF SUMMARY OF THE INVENTION

It is an object of the present invention to eliminate or at leastminimize the above-mentioned problems, and this is done by a methodaccording to the above which is characterized in that a liquid medium issprayed with high kinetic energy onto said roll jacket surface, in thatthe high-kinetic fluid thus forces liquid present on the roll jacketsurface to follow a fluid stream rebounding from the roll jacketsurface, so that the liquid is conveyed to said liquid-collectingdevice.

By virtue of the solution according to the invention, a method isobtained which eliminates or at least minimizes the risk of the rolljacket surface, from which water is to be removed, becoming damaged orworn, since there is no direct physical contact between the roll jacketsurface and the dewatering device. In addition, the dewatering andcleaning (if required) are combined in one and the same step. A furtherimportant advantage is that it has a good dewatering effect (or cleaningeffect) irrespective of whether the roll jacket surface is smooth orpatterned.

According to another aspect of the invention, said medium is water.

By using water as the medium, high kinetic energy is obtained in afavorable manner in the stream of medium used for removing water fromthe roll jacket surface. Tests have shown that a surprisingly goodeffect can be obtained using this medium.

According to another aspect of the invention, said medium is sprayedonto the roll jacket surface at a certain spray angle (α) in relation tothe normal (N) o£ the roll jacket surface, so that an oriented andrebounding fluid stream is created, where α is between 5 and 85° and isa function of the speed (ν) of the roll jacket surface, the spray angle(α) increasing as the speed increases. By virtue of using an acute anglein relation to the roll jacket surface when applying the medium, it ispossible to obtain a controlled rebound of the water which is removedfrom the roll jacket surface.

According to another aspect of the invention, the liquid-collectingdevice is provided with a lip element which is positioned in therebounding fluid stream in order to convey the liquid onwards towardsthe liquid-collecting device. By virtue of the arrangement of a lipelement, the rebounding stream of medium can be collected in a simpleand flexible manner and conveyed to the collecting device.

According to another aspect of the invention, said roll jacket surfacehas irregularities in the form of grooves or cavities in which liquidcan gather. By virtue of the invention, it has been found that it isalso possible to remove water from patterned roll jacket surfaces in anextremely effective way, something which could not be donesatisfactorily by previously known methods, especially not without therisk of damage or undesired wear.

The invention also relates to a device having the same features andadvantages as the method. This, along with further advantages of theinvention, is set out in the description below.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The invention is explained in more detail below with reference to theattached figures, of which:

FIG. 1 is a schematic view of a shoe press with a device for removingwater according to the invention,

FIG. 2 shows a side view of a preferred embodiment of a device forremoving water according to the invention,

FIG. 3 shows a front view of the device according to FIG. 2, and

FIG. 4 shows a preferred principle for how sprays according to theinvention are directed towards a roll jacket surface.

FIG. 5 shows a shoe press device included in a press section in whichthe device and the method according to the invention are used.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic representation of a shoe press roll S which isincluded in a paper-making machine and which cooperates with a counterroll M so that an extended nip for a fiber web W and press felt P isformed between them. A flexible roll jacket 1 is arranged in a knownmanner so that it encloses the shoe press roll S. A device for removingwater according to the invention, with a spray device 2 and aliquid-collecting container 21, is arranged to remove water from theflexible roll jacket 1.

FIG. 2 is a side view of a preferred embodiment of a device for removingwater according to the invention. It will be seen that the device forremoving water is arranged close to the roll jacket surface 1A of aflexible roll jacket 1 which moves upwards at a defined speed (ν) pastthe device for removing water. The liquid-collecting device orliquid-receiving device 21 comprises an elongate container 22 (see alsoFIG. 3) with an axially elongate opening 24 directed towards the rolljacket surface 1A. The opening 24 thus extends parallel to the axialextent of the shoe press roll S around which the flexible, roll jacket 1rotates. With the aid of clamp connections 18A, 18B, the collectingcontainer 22 is adjustably mounted on a circular support part 20 whichin turn is connected securely to a support 17 which is fixed in relationto the paper-making machine. With the aid of screw connections 19, theclamp connections 18A, 18B can be released/secured in order to obtainthe desired positioning of the container 22 in relation to the supportpart 17, 20.

On top of the container 22 there are bracket elements 16 on which afirst adjustable fastening device 8 for the spray device 2 is arranged.This first fastening device 8 makes it possible, on the one hand, toadjust the angle β and on the other hand to adjust the distance betweenthe spray device 2 and the roll jacket surface 1A. In order to changethe angle β, there is a clamp connection 13A, 13B which is fixed on saidbracket 16. This clamp connection 13A, 13B cooperates with a sleeve 15which can be locked at a certain angular position inside the clampconnection by means of screw connection 14. Welded onto said sleeve 15there is an outer pipe-shaped part 10 which cooperates in a telescopicmanner with a rod 9. With the aid of a locking screw 11, the rod 9 canbe locked in different positions, i.e. displaced to different positionsinside the outer pipe-shaped part 10. A plate 7 is arranged at one endof the rod 9. This plate 7 constitutes a rear support for a spray pipe3. The spray pipe 3 is clamped securely against the support plate 7 withthe aid of a conventional pipe clamp 6 which is locked on the plate 7with the aid of nuts 6A, 6B. Arranged on the spray pipe 3 there are anumber of spray nozzles 4 which each have a mouth 4A directed towardsthe roll jacket surface 1A.

Arranged near the lower edge of the opening 24 of the collectingcontainer 22 there is a lip element 26 which projects in the directiontowards the roll jacket surface 1A. With the aid of a screw connection27, the lip element 26 is mounted adjustably on the container 22 so thatthe gap between the roll jacket surface 1A and the front edge of the lipcan be adjusted. At the upper edge of the opening too, and secured bymeans of a screw connection 29, there is an adjustable lip-like device28. The purpose of this last-mentioned device is to vary the size of theopening 24 in order to be able to obtain approximately the same vacuum,which is thus produced by varying the opening vertically along thecontainer. The container 22 is connected at one end to an outlet 23 (seeFIG. 3) connected to an outlet which is under vacuum or communicateswith a vacuum source so that liquid can be actively sucked in throughthe opening 24 of the container 22. By means of the fact that the sizeof the opening can be varied along the container, an identical vacuumcan be obtained along the container opening 24.

FIG. 3 shows the device according to the invention in a front view, i.e.seen from the direction where the roll jacket surface 1A is placed. Mostof the details shown in FIG. 3 are already clear from FIG. 2 and fromthe above description. However, FIG. 3 shows that the spray pipe 3 iselongate and that a large number of spray nozzles 4 are arrangedalongside each other along the spray pipe 3. It will also be seen thateach spray nozzle 4 has a mouth 4A, which in one direction emits adiverging jet (see FIG. 4). It will also be seen that the outlet 23 isarranged at one end of the collecting device 21, which is the reason forthe arrangement of an adjustable upper lip 28, so that the distancebetween the lower edge of this lip 28 and the lower surface 26 of themouth 24 can be varied in the vertical direction along the container. Inthis way, an identical vacuum can be obtained along the whole mouth 24.

FIG. 4 shows that the configuration of the mouth 4A is such that thespray jets follow a diverging pattern, by which means they are sprayedalong a line L3. The mouth 4A of each spray nozzle 4 is set in such away that this spray line L3 is at an acute angle in relation to thecentre line C of the spray pipe 3. In this way, an overlapping of thespray jets on the roll jacket surface 1A is obtained, without twoadjacent spray jets being able to interfere with one another.

Referring to FIG. 1 and FIG. 5, a shoe press roll S is shown with a shoewhich is enclosed by a flexible rotatable roll jacket, which roll jackethas a roll jacket surface 1A. Together with a counter roll M, the shoepress roll S forms a shoe press unit with an extended nip. A press feltP forms a loop around the shoe press roll S, so that the shoe press rollS is located within the felt loop. A spray device 2 is arranged insidethe felt loop and close to the roll jacket surface 1A, which spraydevice is directed towards the roll jacket surface 1A in order to beable to spray a medium onto the roll jacket surface 1A.

Before the device for removing water is started up, the variouscomponents involved are adjusted so as to obtain optimum positions andangles. This is preferably done by first adjusting the angle of thewhole dewatering device with the aid of clamp connections 18A, 18Baround the support part 20. As is shown in the figure, it is preferablyadjusted in such a way that the lip device 26 is arranged substantiallyhorizontally. Alternatively, it can be given a certain rearwardinclination in order to increase the removal capacity with the aid ofgravity. Thereafter, the lip device 26 can be moved so that an optimumgap is formed between the roll jacket surface 1A and the front edge ofthe lip element 26. This is preferably followed by adjusting the angle αat which the spray is directed towards the roll jacket surface 1A inrelation to the normal N of the roll jacket surface. This angle α mustbe such that the medium which is conveyed with the aid of the sprayremoves as much liquid as possible from the roll jacket surface 1A andso that the rebounding fluid stream with liquid L2 impacts the lipelement 26 in the desired manner. It will be appreciated that this angleα must be able to be adapted because different liquids can havedifferent optimum angles of incidence. In the same way, the nature ofthe roll jacket surface 1A is also of course important as regards theoptimum angle of incidence α, especially if, as in the preferred case,it is a question of removing water from a patterned roll jacket surface1A.

The angle of incidence α can be adjusted with the aid of the upper clampconnection 13A, 13B by locking the sleeve 15 in the desired angleposition β. Preferably however, or as a complement to this, thedirection L1 of the spray mouth 4A in relation to the support plate 7 isalso adjusted by locking the spray pipe 3 in a different angle positionby means of the pipe clamp 6. This is preferably followed by adjustingthe distance between the spray mouth 4A and the roll jacket surface 1Aby locking the rod 9 in the desired position with the locking screw 11,so that the optimum spray distance is obtained. The distance that isoptimum will to a large extent depend on how the spray mouths 4 dispensethe medium onto the roll jacket surface 1A. Finally, the height of themouth gap is adapted to the prevailing vacuum by setting the upperlip-shaped element 26 to a suitable position.

The device for removing water functions in such a way that a medium, forexample water, is sprayed via the nozzles 4 at a certain angle ofincidence α and at high pressure onto the roll jacket surface 1A, themedium being given a component of movement which is directed counter tothe movement of the roll jacket surface 1A. The liquid, usually water,present on the roll jacket surface 1A will then combine with the waterwhich is being conveyed at high kinetic energy, after which they jointlyrebound from the flexible roll jacket surface towards the lip element26. From the lip element 26, the water is conveyed towards the mouth 24of the container device 22 by means of the latter being under vacuum.The water is then led off from the container via its outlet 23. Thearrangement thus permits rapid and effective removal of water from theroll jacket surface 1A, and at the same time, if necessary, cleaningthereof. The method is particularly effective in connection withpatterned roll jacket surfaces which cannot always be dewatered (orcleaned) sufficiently well by current methods. In addition, the methodhas the great advantage that there does not need to be any directphysical contact between the roll jacket surface and the device forremoving water, which fact minimizes the risks of wear and risks ofdamage which exist when a flexible roll jacket is in direct contact withany device. Given that these flexible roll jackets are expensive, thisis a not inconsiderable advantage.

By means of the device according to the invention, a press section isalso obtained which includes the device according to the invention.

The invention is not limited by what has been described above, andinstead it can be varied within the scope of the attached patent claims.It will be appreciated that, among other things, the lip element 26 canadvantageously be made of a resilient/flexible material which, in someapplications, can advantageously be arranged in direct contact with theroll jacket surface 1A.

1. A method of removing water from a surface of a flexible rotatable roll jacket of a shoe press roll in a shoe press unit in a wet section of a paper-making machine, the shoe press unit including a counter roll cooperating with the shoe press roll to form an extended press nip for pressing water from a wet fiber web transported thererthrough by a press felt forming a loop about the shoe press roll, the shoe press roll rotating in a direction of travel so as to advance the press felt and the wet fiber web through the extended press nip, said method comprising: directing a spray of a liquid medium from a spray device, disposed within the loop and adjacent to the shoe press roll, toward the roll jacket surface and at least partially against the direction of travel of the shoe press roll, the spray being configured such that the liquid medium contacts the roll jacket surface, collects any water pressed from the wet fiber web remaining on the roll jacket surface, and then rebounds from the roll jacket surface; and collecting the rebounded liquid medium and water from the roll jacket surface with a liquid-receiving device disposed adjacent to and upstream, with respect to the direction of travel of the shoe press roll, of the spray device, the liquid-receiving device having a lip element operably engaged therewith and capable of being extended therefrom toward the roll jacket surface so as to direct the rebounded liquid medium and water from the roll jacket surface toward the liquid-receiving device.
 2. A method according to claim 1 wherein directing a spray further comprises directing a spray toward the roll jacket surface, at least partially against the direction of travel of the shoe press roll, at an angle of between about 5 degrees and about 85 degrees with respect to a normal of the roll jacket surface.
 3. A method according to claim 1 wherein the shoe press roll is rotated at a rotational speed and wherein directing a spray further comprises directing a spray toward the roll jacket surface at an angle, with respect to a normal of the roll jacket surface and at least partially against the direction of travel of the shoe press roll, the angle corresponding to the rotational speed.
 4. A method according to claim 3 wherein directing a spray further comprises increasing the angle of the spray as the rotational speed increases.
 5. A method according to claim 1 wherein the liquid medium and the water from the roll jacket surface rebound from the roll jacket surface in a direction corresponding to an angle at which the spray is directed toward the roll jacket and the method further comprises redirecting the rebounded liquid medium and water to the liquid-receiving device with the lip element.
 6. A method according to claim 5 further comprising adjusting the distance from the lip element to the roll jacket surface.
 7. A method according to claim 1 wherein directing a spray further comprises rotating a pipe having at least one spray nozzle fixed thereto, the pipe and the at least one spray nozzle comprising the spray device, so as to direct the spray toward the roll jacket surface.
 8. A method according to claim 1 wherein the liquid-receiving device is configured to collect the rebounded liquid medium and water from the roll jacket surface through an opening defined thereby and the method further comprises establishing a pressure within the liquid-receiving device and inside the opening lower than a pressure external to the liquid-receiving device and outside the opening so as to provide a suction for collect the rebounded liquid medium and water.
 9. A method according to claim 8 further comprising varying a dimension of the opening.
 10. A method according to claim 1 wherein the liquid medium comprises water and directing a spray further comprises directing a spray of water from the spray device toward the roll jacket surface.
 11. A method according to claim 1 wherein directing a spray further comprises directing the liquid medium into an elongate pipe, defining a longitudinal axis and arranged substantially parallel to the shoe press roll, and through a plurality of spray nozzles arranged longitudinally along the pipe toward the roll jacket surface.
 12. A method according to claim 11 wherein each spray nozzle defines a mouth configured to produce a spray oriented along a jet line and directing the medium further comprises directing the medium through the plurality of spray nozzles, each arranged such that the jet line thereof is disposed at an acute angle with respect to the longitudinal axis of the pipe, toward the roll jacket surface.
 13. A method according to claim 11 wherein each spray nozzle defines a month configured to produce a spray oriented along a jet line and directing the medium further comprises directing the medium through the plurality of spray nozzles, each arranged such that the jet line thereof is disposed at an angle of between about 3 degrees and about 30 degrees with respect to the longitudinal axis of the pipe, toward the roll jacket surface.
 14. A device adapted to remove water from a surface of a flexible rotatable roll jacket of a shoe press roll in a shoe press unit in a wet section of a paper-making machine, the shoe press unit including a counter roll cooperating with the shoe press roll to form an extended press nip for pressing water from a wet fiber web transported therethrough by a press felt forming a loop about the shoe press roll, the shoe press roll rotating in a direction of travel so as to advance the press felt and the wet fiber web through the extended press nip, said device comprising: a spray device disposed within the loop and adjacent to the shoe press roll, the spray device being configured to direct a spray of a liquid medium toward the roll jacket surface and at least partially against the direction of travel of the shoe press roll, the spray being configured such that the liquid medium contacts the roll jacket surface, collects any water pressed from the wet fiber web remaining on the roll jacket surface, and then rebounds from the roll jacket surface; and a liquid-receiving device disposed adjacent to and upstream, with respect to the direction of travel of the shoe press roll, of the spray device and having a lip element operably engaged therewith and capable of being extended therefrom toward the roll jacket surface so as to direct the rebounded liquid medium and water from the roll jacket surface toward the liquid-receiving device.
 15. A device according to claim 14 wherein the spray device is further configured to direct the spray toward the roll jacket surface, at least partially against the direction of travel of the shoe press roll, at an angle of between about 5 degrees and about 85 degrees with respect to a normal of the roll jacket surface.
 16. A device according to claim 14 wherein the shoe press roll is rotated at a rotational speed and wherein the spray device is further configured to direct the spray toward the roll jacket surface at an angle, with respect to a normal of the roll jacket surface and at least partially against the direction of travel of the shoe press roll, corresponding to the rotational speed, the angle of the spray increasing as the rotational speed increases.
 17. A device according to claim 14 wherein the lip element is movable with respect to the liquid-receiving device such that the distance from the lip element to the roll jacket surface is adjustable.
 18. A device according to claim 14 wherein the spray device further comprises a pipe having at least one spray nozzle fixed thereto, the pipe being rotatable so as to move the at least one spray nozzle to direct the spray toward the roll jacket surface.
 19. A device according to claim 14 wherein the liquid-receiving device is configured to collect the rebounded liquid medium and water from the roll jacket surface through an opening defined thereby, the opening extending longitudinally in opposing relation to the roll jacket surface.
 20. A device according to claim 19 wherein the liquid-receiving device further comprises a container operably engaged with the opening, the container having a suction applied thereto through an outlet, whereby the applied suction extends through the opening for collecting the rebounded liquid medium and water.
 21. A device according to claim 19 wherein the opening of the liquid-receiving device is configured such that a dimension of the opening is capable of being varied.
 22. A device according to claim 14 wherein the liquid medium further comprises water.
 23. A device according to claim 14 wherein the spray device further comprises an elongate pipe, defining a longitudinal axis and arranged substantially parallel to the shoe press roll, and a plurality of spray nozzles arranged longitudinally along the pipe, the liquid medium being received by the pipe and discharged toward the roll jacket surface through the spray nozzles.
 24. A device according to claim 23 wherein each spray nozzle defines a mouth configured to produce a spray oriented along a jet line and each spray nozzle is arranged such that the jet line thereof is disposed at an angle of between about 3 degrees and about 30 degrees with respect to the longitudinal axis of the pipe.
 25. A press section of a paper-making machine, comprising: a shoe press unit including a shoe press roll having a flexible rotatable roll jacket and a counter roll cooperating with the shoe press roll to form an extended press nip adapted to press water from a wet fiber web transported therethrough by a press felt forming a loop about the shoe press roll, the shoe press roll rotating in a direction of travel so as to advance the press felt and die wet fiber web through the extended press nip; and a device disposed within the loop and adapted to remove water from a surface of the roll jacket, the device comprising: a spray device dispose adjacent to the shoe press roll, the spray device being configured to direct a spray of a liquid medium toward the roll jacket surface and at least partially against the direction of travel of the shoe press roll, the spray being configured such that the liquid medium contacts the roll jacket surface, collects any water pressed from the wet fiber web remaining on the roll jacket surface, and then rebounds from the roll jacket surface; and a liquid-receiving device disposed adjacent to and upstream, with respect to the direction of travel of the shoe press roll, of the spray device and having a lip element operably engaged therewith and capable being extended therefrom toward the roll jacket surface so as to direct the rebounded liquid medium and water from the roll jacket surface toward the liquid-receiving device.
 26. A press section according to claim 25 wherein the spray device is further configured to direct the spray toward the roll jacket surface, at least partially against the direction of travel of the shoe press roll, at an angle of between about 5 degrees and about 85 degrees with respect to a normal of the roll jacket surface.
 27. A press section according to claim 25 wherein the shoe press roll is rotated at a rotational speed and wherein the spray device is further configured to direct the spray toward the roll jacket surface at an angle, with respect to a normal of the roll jacket surface and at least partially against the direction of travel of the shoe press roll, corresponding to the rotational speed, the angle of the spray increasing as the rotational speed increases.
 28. A press section according to claim 25 wherein the lip element is movable with respect to the liquid-receiving device such that the distance from the lip element to the roll jacket surface is adjustable.
 29. A press section according to claim 25 wherein the spray device further comprises a pipe having least one spray nozzle fixed thereto, the pipe being rotatable so as to move the at least one spray nozzle to direct the spray toward the roll jacket surface.
 30. A press section according to claim 25 wherein the liquid-receiving device is configured to collect the rebounded liquid medium and water from the roll jacket surface through an opening defined thereby, the opening extending longitudinally in opposing relation to the roll jacket surface.
 31. A press section according to claim 30 wherein the liquid-receiving device further comprises a container operably engaged with the opening, the container having a suction applied thereto through an outlet, whereby the applied suction extends through the opening for collecting the rebounded liquid medium and water.
 32. A press section according to claim 30 wherein the opening of the liquid-receiving device is configured such that a dimension of the opening is capable of being varied.
 33. A press section according to claim 25 wherein the liquid medium further comprises water.
 34. A press section according to claim 25 wherein the spray device further comprises an elongate pipe, defining a longitudinal axis and arranged substantially parallel to the shoe press roll, and a plurality of spray nozzles arranged longitudinally along the pipe, the liquid medium being received by the pipe and discharged toward the roll jacket surface through the spray nozzles.
 35. A press section according to claim 34 wherein each spray nozzle defines a mouth configured to produce a spray oriented along a jet line and each spray nozzle is arranged such that the jet line thereof is disposed at an angle of between about 3 degrees and about 30 degrees with respect to the longitudinal axis of the pipe. 